Technical Field
The present invention generally relates to sensing devices. More specifically, the present invention relates to a piezoelectric thin-film based flexible sensing device, a method for fabrication thereof, and a method for operating the same.
Description of the Related Art
Various techniques for sensing impact events, and in particular, force and/or pressure have been investigated in the art in recent years. Such sensors include for example, mechanoluminescence detection, fibre-optical properties of semiconductor materials based sensor, wide spectrum acoustic emission (AE) wave-based sensors, and inertial mass variation based sensors. Such sensors require complex fabrication process, high accuracy adjunct measurement instruments, dedicated setting up, and not the least, highly skilled technicians to carry out the measurements. The prior art techniques are not only expensive but also lack desired versatility.
Detection and measurement techniques using bulk piezo-ceramics and readily available polyvinylidene fluoride (PVDF) films have also been reported. However, the integration of the bulk materials and PVDF wearable films with Micro Electro Mechanical System (MEMS) requires state-of-the-art fabrication techniques. Such emerging techniques are still in early stages of research and are not commercially viable owing to difficulty in miniaturization and challenges in designing batch fabrication processes for mass production of such sensors.
While research efforts have been made to integrate piezoelectric materials in thin-film transistors produced using standard semiconductor fabrication process, the inherent constraint related to process temperature remains unaddressed. Various piezoelectric materials have a relatively low Curie point (90° C.), above which the piezoelectric properties are lost. Thus, traditional fabrications techniques employed for silicon transistors, which usually require higher temperatures, inherently prohibit integrating piezoelectric thin-films with standard transistors.
In light of the foregoing, there is a need for providing a flexible sensing device conducive to low cost fabrication under low temperature conditions and providing enhanced sensitivity.